1. Field of the Invention
The present invention relates to a jet propelled watercraft.
2. Description of the Related Art
There is a well-known type of jet propelled watercraft that can set a variety of modes in accordance with cruising conditions. For example, Japan Laid-open Patent Application Publication No. 2005-9388 describes a jet propelled watercraft that enables a vessel operator to select a steering angle correspondence mode. In this steering angle correspondence mode, a driving force is reduced when the jet propelled watercraft turns during high velocity forward cruising. With this configuration, turning performance of the jet propelled watercraft can be enhanced.
On the other hand, Japan Laid-open Patent Application Publication No. 2005-16354 describes a jet propelled watercraft in which a predetermined upper limit is set for a throttle opening degree so as to reduce an engine output more during backward movement than during forward movement. With this setting, the engine output is limited during backward movement, and high velocity cruising can be prevented during backward movement.
The jet propelled watercraft described in Japan Laid-open Patent Application Publication No. 2005-16354 can select either a medium velocity cruising mode or a low velocity cruising mode as an engine output characteristic. However, the upper limit of the throttle opening degree during backward movement is fixed to the same value in both the medium velocity cruising mode and the low velocity cruising mode.
In the jet propelled watercraft, either a deceleration force or the vessel velocity during backward movement is regulated by regulating a backward thrust in response to operating an accelerator lever. However, a vessel operator such as a novice operator, who is not familiar with operating the vessel, is likely to fully squeeze the accelerator lever during deceleration. Therefore, when the upper limit of the throttle opening degree during backward movement is fixed as described above, it is not easy to regulate the backward thrust at an intended magnitude in accordance with vessel body conditions. Hence, when the vessel velocity is reduced as with the steering angle correspondence mode described in Japan Laid-open Patent Application Publication No. 2005-9388, there is too much deceleration and the behavior of the vessel body becomes easily unstable. As a result, there is a room for improvement in easily regulating a backward thrust in accordance with the vessel body conditions such as the vessel velocity during forward movement.